Open Activity Tracker Framework

The MHSL Activity tracker was originally developed at the Mobile Health Systems Lab at ETH Zürich and is a wearable electronics module that builds the core of the open-​source physical activity tracking framework.

Key features:

• High-​end, low power 3-​axis accelerometer operating at up to 400 Hz, with a selectable acceleration range of ±2g, ±4g, and ±8g (ADXL363)
• 16 MB on-​device Flash memory IS25LP128 (enables approx. 48 hours of raw data recording from 3 axis, at 12-​bit resolution and 12.5Hz sampling rate)
• Up to 6 months of stand-​alone use, storing one 16-​bit-word/minute
• Bluetooth connectivity for real-​time or offline data acquisition
• Powered by an exchangeable coin-​cell battery (CR3032) providing up to 6 months life-​time
• Button and 2 LEDs for simple user interaction
• Small, circular PCB with all electronics integrated (2.5cm in diameter)
• 3D-​printed housing for modular packaging solution (current version supports attachment of Swatch armbands and enclosing into velcro elastic bands for comfortable wearing at the wrist and ankle)
• Open-​source mobile app (Android) for actimeter configuration and data collection, analysis, and visualization
• Open-​hardware for easy adaptation of housing or changing electronic components according to projects-​specific requirements
• Large selection of open-​source algorithms tested for various applications (activity measure, sleep tracking) and wearing positions (ankle, hip, and wrist)

Research projects where the framework was in use:

ETH Scientifica (2017): Twenty actimeters have been successfully used at the 2017 ETH Scientifica citizen-​science project “Was sagen Aktivitätsarmbänder und SmartWatches wirklich über unsere Aktivität aus?» demonstrating a MIDATA integration with different health applications.

SNF NFP75 Big-Data (2019-2020):  The actimeters have been used to monitor low-back pain patients during the intervention period in a clinical trial investigating exergaming interventions. 

Meinke, A., Peters, R., Knols, R., Karlen, W., & Swanenburg, J. (2021). Exergaming Using Postural Feedback From Wearable Sensors and Exercise Therapy to Improve Postural Balance in People With Unspecific Low Back Pain: Protocol for a Factorial Pilot Randomized Controlled Trial. (Preprint). JMIR Research Protocols. https://doi.org/10.2196/26982

Developers and Collaborators:

Prof. Walter Karlen, Dr. Jelena Dragas, 

We are collaborating with a Swiss-​based startup Leitwert GmbH who have designed the hardware and real time embedded software.

Prof. Dr. Christina Spengler, Exercise Physiology Lab, ETH Zürich

Publications